Horton's core area of research is plasma transport and its application to the development of nuclear fusion power.
Horton's interest in nuclear fusion grew during his graduate studies at the University of California at San Diego.
Horton earned his PhD at UCSD under Marshall Rosenbluth, a scientist who had worked on the Manhattan Project and a close protégé of Edward Teller.
Horton has published or edited thirteen books on the theoretical basis for plasma containment and transport, and co-authored over 200 papers.
However, the quest for fusion containment in a laboratory has been the biggest source of contribution and inspiration during his 40-year career in theoretical physics.